1. Field of the Invention
Embodiments of the present invention relate to a method of preventing electrostatic discharge during connection of a USB-type connector, and a USB-type connector formed thereby.
2. Description of the Related Art
The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large storage capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
Equally ubiquitous is the universal serial bus (USB) interface for transferring signals between devices such as those named above and other components such as for example desktop computers and the like. The USB interface is comprised of a male plug and female socket connectors. Plugs generally have one or more pins that are inserted into openings in the mating socket. While there are several types of USB connectors, the most commonly used is the type-A plug on which is a 4-pin connector, surrounded by a shield. A conventional type-A USB plug and socket are shown in cross-section in prior art FIGS. 1 through 3. The conventional USB plug 20 shown in FIG. 1 may for example be attached to an electronic device and includes a base 22 on which is formed a signal power pin 24, a pair of signal pins 26, 28 and a signal ground pin 30. The base and pins are covered by a shroud 32. The conventional USB socket 36 may be incorporated in a host device and includes a base 38 and four terminals 40 through 46 formed thereon. As seen in FIG. 3, the plug may be received within the socket with pins 24 through 30 mating with pins 40 through 46 to allow transfer of signals between the electronic and host devices.
In conventional USB connections, the shroud is electrically coupled to the signal ground pin through an established circuit path in the electronic device. In particular, once affixed around the base 22 and pins 26 through 30, the shroud may typically be soldered to a printed circuit board at a location coupled to the signal ground pin. One of the functions of the electrical coupling of the shroud to ground is to prevent electrostatic discharge (ESD) between the shroud and portions of the circuit of the electronic device. In particular, where the shroud and electronic circuit are at different electrical potentials (for example due to static electrical build-up in the shroud), an electrostatic charge may jump from the shroud onto the electronic circuit, where the electrostatic charge may damage semiconductor components in the circuit.
As indicated, where the shroud is grounded, electrostatic charge in the shroud may be discharged harmlessly through the grounded connection. However, it is currently known to provide USB connective semiconductor devices where a shroud is included, but is not soldered to the printed circuit board and has no ground connection. Such devices run the risk of damage due to ESD between the shroud and electronic circuit.